A wide variety of airway devices are used to provide gas (e.g., oxygen) to a mammal's airway. Examples of airway devices include face masks, endotracheal tubes, and laryngeal devices.
A face mask covers the mouth and nose of a patient. Face masks are non-invasive, since the sealing of the airway is accomplished not by penetration into the patient's airway, but by covering the mouth and nose of the patient. However, airway patency is not assured since the tongue and other structures can still obstruct the airway. Also, it is difficult to maintain a seal of the airway for any period of time, particularly during positive pressure ventilation. Leakage around the face mask results in ineffective ventilation and, during anesthesia, contaminates the operating room with anesthetic gases. Furthermore, a face mask does not prevent the introduction of air into the esophagus and stomach (gastric insufflation) or protect against the aspiration of stomach contents (e.g., breathing of vomited material).
Endotracheal tubes are inserted through the mouth or nose and into the trachea (the windpipe) where a cuff surrounding the tube seals against the interior surface of the trachea. This approach avoids the deficiencies of face masks because it includes a conduit traversing the pharynx, and forms an effective seal against the airway, allowing positive pressure ventilation, and protection against the aspiration of stomach contents.
While solving several problems, endotracheal tubes create new challenges. They are difficult to insert and position properly within the trachea, almost always requiring a laryngoscope, stylet or other intubation aid. Penetration of the larynx and trachea is invasive and is a highly noxious stimulus requiring anesthesia. Furthermore, once in place or even during the insertion process, endotracheal tubes can injure the delicate tissue of the larynx and trachea including the vocal cords. In some instances, endotracheal tubes can cause bleeding, swelling, laryngospasms, patient discomfort and hoarseness. Incorrect positioning of the tip of an endotracheal tube (distally into the mainstem bronchi or proximal dislocation out of the trachea) is an additional concern.
Another type of airway device is a laryngeal airway device. Laryngeal airway devices provide a more direct supply of gas to the trachea than a face mask and are not inserted into the trachea. One type of laryngeal device has an air tube with proximal and distal ends and a padded, sealing member that is attached to the distal end of the air tube. The sealing member can be made of a closed cell foam or can be inflatable. In both instances, the sealing member is in the form of a spoon-shaped cuff that surrounds a hole that provides air to the trachea. When this type of laryngeal airway device is used, the sealing member is seated in the throat of the mammal and the hole in the sealing member is in communication with the distal end of the air tube. Air is supplied to the trachea through the air tube and through the hole in the sealing member.
While the described laryngeal airway device addresses some of the concerns of face masks and the described endotracheal tubes, a number of other problems remain. For example, the padded, sealing member of the described laryngeal airway device is relatively large. The mammal using the laryngeal airway device may be small (e.g., less than 10 pounds) and it may be difficult to insert the sealing member into the mouth and down the throat of the small mammal. It can also be difficult to properly position the air hole in the sealing member over the larynx. It is also difficult to position the sealing member so that it is lodged in the esophagus to stop any fluids (e.g., gastric juices) from coming up from the stomach. Furthermore, the wide sealing member can sometimes cause the epiglottis to fold and block the larynx, thus inhibiting lung ventilation. The wide sealing member can also injure the larynx and obstruct the mammal's airway, especially when it becomes dislocated within the mammal's throat.
Accordingly, improved airway devices and methods for using the same would be desirable. Embodiments of the invention address these and other problems.